1. Filed of the Invention
The present invention relates generally to prosthetic feet and, more particularly, to a prosthetic foot having a cushioned ankle and a thong-receiving reinforced outer foot cosmesis.
2. Description of the Related Art
In the prosthetics market, the conventional SACH foot has been the most widely prescribed artificial foot over the past several decades. The SACH foot generally includes a solid ankle and cushioned heel foot mounted to a limb along an approximate hinge axis taken through the ankle. The SACH foot has been popular precisely for its simplicity, and thus economy, but includes certain drawbacks in terms of dynamic response characteristics. Specifically, the low end SACH feet do not provide much energy storage and release, as do more sophisticated prosthetic feet.
Some patients undergo what is known in the art as a Symes amputation, where the foot is severed from the leg near the ankle region. Because the Symes patient""s calf and shin function as the stump for prosthetic purposes, prosthetic devices utilized by the patient must either be relatively compact, so as to be attachable below the point of amputation, or must be configured to accommodate the patient""s shin and calf while attached thereto or higher up on the wearer""s leg.
Prior art prostheses available to Symes patients typically include an artificial foot bonded or bolted onto the bottom end of a socket worn on a patient""s stump. These compact prosthetic feet can also attach below a downwardly depending pylon secured to a socket higher up on the amputee""s leg. For such compact prostheses, it is difficult to provide the level of dynamic response approximating the original ankle and foot due to the lack of vertical space available.
Some attempts at providing the appropriate response characteristics of the original ankle and foot in Symes foot prosthesis involve the use of rubber cushions, or bumpers, between a lower leg and the foot. Many of these require a pivotable bolt attachment between the leg and the foot. Unfortunately, many of these rubber cushion devices have limited durability due to the difficulty in bonding the rubber portions to the solid leg or foot portions, or are relatively complex, requiring several machined parts, which adds to the cost.
U.S. Pat. Nos. 5,800,569 and 5,993,488, incorporated by reference herein, to Phillips disclose a resilient ankle block prosthesis that mitigates or overcomes some of the above disadvantages. But, there is still room for further improvements in providing a smooth and more natural-feeling rollover from a heel-strike to a toe-off position and/or of providing improved dynamic response characteristics, so as to provide a natural feeling foot during walking or running activities.
There are also a number of foot cosmesis that are presently commercially available in the market. The cosmesis for an artificial foot serves as a cosmetic outer cover and provides the appearance of a relatively natural looking foot for the lower limb amputee.
Conventional artificial feet and/or cosmesis can disadvantageously also be limited in terms of the flexibility and versatility they provide in allowing the amputee to don different types of conventional footwear. Moreover, the frictional contact between the artificial foot and the cosmesis can cause wear of the cosmesis, especially at the high stress contact points. This can not only result in inconvenient frequent replacement of the cosmesis but also further adds to the cost for the amputee. Additionally, many artificial feet are adapted to be used only as a left or right foot and not both, and this undesirably limits versatility and increases manufacturing and inventory costs.
Consequently, there is a need for a relatively inexpensive, durable and versatile prosthetic foot assembly with improved performance characteristics.
Accordingly, it is one object and advantage of the present invention to overcome some or all of the above limitations by providing a cushioned ankle prosthetic foot and an associated cosmesis having a slot between the big toe and adjacent toe to allow the amputee to wear thong sandals and the like. The cushioning desirably provides a smooth and more natural-feeling rollover from a heel-strike to a toe-off position and/or improved dynamic response characteristics. Advantageously, the prosthetic foot is configured so that it can be used as either a right or a left foot. Moreover, the cosmesis includes a toe reinforcement strap to desirably provide improved wear resistance to the cosmesis.
In accordance with one preferred embodiment of the invention, a prosthetic foot assembly for a lower limb amputee is provided. The assembly generally comprises a prosthetic foot and an outer cosmesis. The prosthetic foot attaches to a socket or pylon of the lower limb amputee. The prosthetic foot generally comprises a lower foot plate and an upper ankle plate. The lower foot plate includes a symmetric toe configuration and a plurality of slots formed therebetween. The upper ankle plate has a length substantially shorter than the foot plate. The prosthetic foot further comprises an ankle block having a wedged configuration. The ankle block comprises a compressible material and is sandwiched between the foot plate and the ankle plate. The outer cosmesis has a length approximately equal to the length of a natural human foot and has an anterior toe region including a slot substantially aligned with one of the slots of the foot plate. Advantageously, the prosthetic foot assembly permits the lower limb amputee to wear thong sandals and the like and/or provides enhanced performance characteristics.
In accordance with another preferred embodiment of the invention, an outer foot cosmesis is provided. The outer foot cosmesis has a length substantially the same as that of a natural human foot. The cosmesis comprises an inner cavity for receiving a prosthetic foot for attaching to a socket or pylon of a lower limb amputee. The cosmesis has a toe portion comprising at least one slot for receiving a thong of a sandal or other footwear. The cosmesis further comprises a reinforcement patch in the toe portion for improving the wear resistance of the cosmesis.
For purposes of summarizing the invention and the advantages achieved over the prior art, certain objects and advantages of the invention have been described herein above. Of course, it is to be understood that not necessarily all such objects or advantages may be achieved in accordance with any particular embodiment of the invention. Thus, for example, those skilled in the art will recognize that the invention may be embodied or carried out in a manner that achieves or optimizes one advantage or group of advantages as taught herein without necessarily achieving other objects or advantages as may be taught or suggested herein.
All of these embodiments are intended to be within the scope of the invention herein disclosed. These and other embodiments of the present invention will become readily apparent to those skilled in the art from the following detailed description of the preferred embodiments having reference to the attached figures, the invention not being limited to any particular preferred embodiment(s) disclosed.